#!/usr/bin/python
#
# Copyright (c) 2012 The Chromium Authors. All rights reserved.
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.

"""Creates a GYP include file for building FFmpeg from source.

The way this works is a bit silly but it's easier than reverse engineering
FFmpeg's configure scripts and Makefiles. It scans through build directories for
object files then does a reverse lookup against the FFmpeg source tree to find
the corresponding C or assembly file.

Running build_ffmpeg.sh for ia32, arm, arm-neon and mips32 platforms is
required prior to running this script. The arm, arm-neon and mips32 platforms
assume a Chromium OS build environment.

The Ensemble branding supports the following architectures: ia32, x86, arm, and
mipsel.

Step 1: Have a Chromium OS checkout (refer to http://dev.chromium.org)
  mkdir chromeos
  repo init ...
  repo sync

Step 2: Check out deps/third_party/ffmpeg inside Chromium OS (or cp -fpr it over
from an existing checkout; symlinks and mount --bind no longer appear to enable
access from within chroot)
  cd path/to/chromeos
  mkdir deps
  cd deps
  git clone http://git.chromium.org/chromium/third_party/ffmpeg.git

Step 3: Build for ia32 platform outside chroot (will need yasm in path)
  cd path/to/chromeos/deps/ffmpeg
  ./chromium/scripts/build_ffmpeg.sh linux ia32 path/to/chromeos/deps/ffmpeg

Step 4: Build and enter Chromium OS chroot:
  cd path/to/chromeos/src/scripts
  cros_sdk --enter

Step 5: Setup build environment for ARM:
  ./setup_board --board arm-generic

Step 6: Build for arm/arm-neon platforms inside chroot
  ./chromium/scripts/build_ffmpeg.sh linux arm path/to/chromeos/deps/ffmpeg
  ./chromium/scripts/build_ffmpeg.sh linux arm-neon path/to/chromeos/deps/ffmpeg

Step 7: Setup build environment for MIPS:
  ./setup_board --board mipsel-o32-generic

Step 8: Build for mipsel platform inside chroot
  ./chromium/scripts/build_ffmpeg.py linux mipsel

Step 9: Build for Windows platform; you will need a MinGW shell started from
inside a Visual Studio Command Prompt to run build_ffmpeg.sh:
  ./chromium/scripts/build_ffmpeg.sh win ia32 $(pwd)

Step 10: Exit chroot and generate gyp file
  exit
  cd path/to/chromeos/deps/ffmpeg
  ./chromium/scripts/generate_gyp.py

Phew!

While this seems insane, reverse engineering and maintaining a gyp file by hand
is significantly more painful.
"""

__author__ = 'scherkus@chromium.org (Andrew Scherkus)'

import collections
import datetime
import fnmatch
import itertools
import optparse
import os
import re
import string
import subprocess
import shutil

COPYRIGHT = """# Copyright %d The Chromium Authors. All rights reserved.
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.

# NOTE: this file is autogenerated by ffmpeg/chromium/scripts/generate_gyp.py

""" % (datetime.datetime.now().year)

GYP_HEADER = """
{
  'variables': {
"""

GYP_FOOTER = """  },
}
"""


GYP_CONDITIONAL_BEGIN = """    'conditions': [
"""
GYP_CONDITIONAL_END = """    ],  # conditions
"""
GYP_CONDITIONAL_STANZA_BEGIN = """      ['%s', {
"""
GYP_CONDITIONAL_STANZA_ITEM = """          '%s',
"""
GYP_CONDITIONAL_STANZA_OUTPUT_ITEM = """          '<(shared_generated_dir)/%s',
"""
GYP_CONDITIONAL_STANZA_END = """      }],  # %s
"""

GYP_CONDITIONAL_C_SOURCE_STANZA_BEGIN = """        'c_sources': [
"""
GYP_CONDITIONAL_ASM_SOURCE_STANZA_BEGIN = """        'asm_sources': [
"""
GYP_CONDITIONAL_ITEM_STANZA_END = """        ],
"""

GN_HEADER = """import("//build/config/arm.gni")
import("ffmpeg_options.gni")

# Declare empty versions of each variable for easier +=ing later.
ffmpeg_c_sources = []
ffmpeg_gas_sources = []
ffmpeg_yasm_sources = []

"""
GN_CONDITION_BEGIN = """if (%s) {
"""
GN_CONDITION_END = """}

"""
GN_C_SOURCES_BEGIN = """ffmpeg_c_sources += [
"""
GN_GAS_SOURCES_BEGIN = """ffmpeg_gas_sources += [
"""
GN_YASM_SOURCES_BEGIN = """ffmpeg_yasm_sources += [
"""
GN_SOURCE_ITEM = """  "%s",
"""
GN_SOURCE_END = """]
"""

# Controls GYP conditional stanza generation.
SUPPORTED_ARCHITECTURES = ['ia32', 'arm', 'arm-neon', 'x64', 'mipsel']
SUPPORTED_TARGETS = ['Chromium', 'Chrome', 'ChromiumOS', 'ChromeOS', 'Ensemble']
# Mac doesn't have any platform specific files, so just use linux and win.
SUPPORTED_PLATFORMS = ['linux', 'win']


def NormalizeFilename(name):
  """ Removes leading path separators in an attempt to normalize paths."""
  return string.lstrip(name, os.sep)


def CleanObjectFiles(object_files):
  """Removes unneeded object files due to linker errors, binary size, etc...

  Args:
    object_files: List of object files that needs cleaning.
  """
  blacklist = [
      'libavcodec/inverse.o',  # Includes libavutil/inverse.c
      'libavcodec/file_open.o', # Includes libavutil/file_open.c
      'libavcodec/log2_tab.o',  # Includes libavutil/log2_tab.c
      'libavformat/golomb_tab.o',  # Includes libavcodec/golomb.c
      'libavformat/log2_tab.o',  # Includes libavutil/log2_tab.c
      'libavformat/file_open.o', # Includes libavutil/file_open.c

      # The following files are removed to trim down on binary size.
      # TODO(ihf): Warning, it is *easy* right now to remove more files
      # than is healthy and end up with a library that the linker does
      # not complain about but that can't be loaded. Add some verification!
      'libavcodec/audioconvert.o',
      'libavcodec/resample.o',
      'libavcodec/resample2.o',
      'libavcodec/x86/dnxhd_mmx.o',
      'libavformat/sdp.o',
      'libavutil/adler32.o',
      'libavutil/audio_fifo.o',
      'libavutil/aes.o',
      'libavutil/blowfish.o',
      'libavutil/cast5.o',
      'libavutil/des.o',
      'libavutil/file.o',
      'libavutil/hash.o',
      'libavutil/hmac.o',
      'libavutil/lls.o',
      'libavutil/murmur3.o',
      'libavutil/rc4.o',
      'libavutil/ripemd.o',
      'libavutil/sha512.o',
      'libavutil/tree.o',
      'libavutil/xtea.o',
      'libavutil/xga_font_data.o',
  ]
  for name in blacklist:
    name = name.replace('/', os.sep)
    if name in object_files:
      object_files.remove(name)
  return object_files

def IsAssemblyFile(f):
  _, ext = os.path.splitext(f)
  return ext in ['.S', '.asm']

def IsGasFile(f):
  _, ext = os.path.splitext(f)
  return ext in ['.S']

def IsYasmFile(f):
  _, ext = os.path.splitext(f)
  return ext in ['.asm']

def IsCFile(f):
  _, ext = os.path.splitext(f)
  return ext in ['.c']

def IsSourceFile(f):
  return IsAssemblyFile(f) or IsCFile(f)

def GetSourceFiles(source_dir):
  """Returns a list of source files for the given source directory.

  Args:
    source_dir: Path to build a source mapping for.

  Returns:
    A python list of source file paths.
  """

  def IsSourceDir(d):
    return d not in ['.git', '.svn']

  source_files = []
  for root, dirs, files in os.walk(source_dir):
    dirs = filter(IsSourceDir, dirs)
    files = filter(IsSourceFile, files)

    # Strip leading source_dir from root.
    root = root[len(source_dir):]
    source_files.extend([NormalizeFilename(os.path.join(root, name)) for name in
                         files])
  return source_files


def GetObjectFiles(build_dir):
  """Returns a list of object files for the given build directory.

  Args:
    build_dir: Path to build an object file list for.

  Returns:
    A python list of object files paths.
  """
  object_files = []
  for root, dirs, files in os.walk(build_dir):
    # Strip leading build_dir from root.
    root = root[len(build_dir):]

    for name in files:
      _, ext = os.path.splitext(name)
      if ext == '.o':
        name = NormalizeFilename(os.path.join(root, name))
        object_files.append(name)
  CleanObjectFiles(object_files)
  return object_files


def GetObjectToSourceMapping(source_files):
  """Returns a map of object file paths to source file paths.

  Args:
    source_files: List of source file paths.

  Returns:
    Map with object file paths as keys and source file paths as values.
  """
  object_to_sources = {}
  for name in source_files:
    basename, ext = os.path.splitext(name)
    key = basename + '.o'
    object_to_sources[key] = name
  return object_to_sources


def GetSourceFileSet(object_to_sources, object_files):
  """Determines set of source files given object files.

  Args:
    object_to_sources: A dictionary of object to source file paths.
    object_files: A list of object file paths.

  Returns:
    A python set of source files required to build said objects.
  """
  source_set = set()
  for name in object_files:
    # Intentially raise a KeyError if lookup fails since something is messed
    # up with our source and object lists.
    source_set.add(object_to_sources[name])
  return source_set


class SourceSet(object):
  """A SourceSet represents a set of source files that are built on the given
  set of architectures and targets.
  """

  def __init__(self, sources, architectures, targets, platforms):
    """Creates a SourceSet.

    Args:
      sources: a python set of source files
      architectures: a python set of architectures (i.e., arm, x64, mipsel)
      targets: a python set of targets (i.e., Chromium, Chrome)
      platforms: a python set of platforms (i.e., win, linux)
    """
    self.sources = sources
    self.architectures = architectures
    self.targets = targets
    self.platforms = platforms

  def __repr__(self):
    return '{%s, %s, %s, %s}' % (self.sources, self.architectures, self.targets,
                                 self.platforms)

  def __eq__(self, other):
    return (self.sources == other.sources and
            self.architectures == other.architectures and
            self.targets == other.targets and
            self.platforms == other.platforms)

  def Intersect(self, other):
    """Return a new SourceSet containing the set of source files common to both
    this and the other SourceSet.

    The resulting SourceSet represents the union of the architectures and
    targets of this and the other SourceSet.
    """
    return SourceSet(self.sources & other.sources,
                     self.architectures | other.architectures,
                     self.targets | other.targets,
                     self.platforms | other.platforms)

  def Difference(self, other):
    """Return a new SourceSet containing the set of source files not present in
    the other SourceSet.

    The resulting SourceSet represents the intersection of the architectures and
    targets of this and the other SourceSet.
    """
    return SourceSet(self.sources - other.sources,
                     self.architectures & other.architectures,
                     self.targets & other.targets,
                     self.platforms & other.platforms)

  def IsEmpty(self):
    """An empty SourceSet is defined as containing no source files or no
    architecture/target (i.e., a set of files that aren't built on anywhere).
    """
    return (len(self.sources) == 0 or len(self.architectures) == 0 or
            len(self.targets) == 0 or len(self.platforms) == 0)

  def GenerateGypStanza(self):
    """Generates a gyp conditional stanza representing this source set.

    TODO(scherkus): Having all this special case condition optimizing logic in
    here feels a bit dirty, but hey it works. Perhaps refactor if it starts
    getting out of hand.

    Returns:
      A string of gyp code.
    """

    # Only build a non-trivial conditional if it's a subset of all supported
    # architectures.
    arch_conditions = []
    if self.architectures == set(SUPPORTED_ARCHITECTURES):
      arch_conditions.append('1')
    else:
      for arch in self.architectures:
        if arch == 'arm-neon':
          arch_conditions.append('(target_arch == "arm" and arm_neon == 1)')
        else:
          arch_conditions.append('target_arch == "%s"' % arch)

    # Only build a non-trivial conditional if it's a subset of all supported
    # targets.
    branding_conditions = []
    if self.targets == set(SUPPORTED_TARGETS):
      branding_conditions.append('1')
    else:
      for branding in self.targets:
        branding_conditions.append('ffmpeg_branding == "%s"' % branding)

    platform_conditions = []
    if (self.platforms == set(SUPPORTED_PLATFORMS) or
        self.platforms == set(['linux'])):
      platform_conditions.append('1')
    else:
      for platform in self.platforms:
        platform_conditions.append('OS == "%s"' % platform)

    conditions = '(%s) and (%s) and (%s)' % (' or '.join(arch_conditions),
                                             ' or '.join(branding_conditions),
                                             ' or '.join(platform_conditions))

    stanza = []
    stanza += GYP_CONDITIONAL_STANZA_BEGIN % (conditions)

    self.sources = sorted(n.replace('\\', '/') for n in self.sources)

    # Write out all C sources.
    c_sources = filter(IsCFile, self.sources)
    if c_sources:
      stanza += GYP_CONDITIONAL_C_SOURCE_STANZA_BEGIN
      for name in c_sources:
        stanza += GYP_CONDITIONAL_STANZA_ITEM % (name)
      stanza += GYP_CONDITIONAL_ITEM_STANZA_END

    # Write out all assembly sources.
    asm_sources = filter(IsAssemblyFile, self.sources)
    if asm_sources:
      stanza += GYP_CONDITIONAL_ASM_SOURCE_STANZA_BEGIN
      for name in asm_sources:
        stanza += GYP_CONDITIONAL_STANZA_ITEM % (name)
      stanza += GYP_CONDITIONAL_ITEM_STANZA_END

    stanza += GYP_CONDITIONAL_STANZA_END % (conditions)
    return ''.join(stanza)

  def GenerateGnStanza(self):
    """Generates a gyp conditional stanza representing this source set.

    TODO(scherkus): Having all this special case condition optimizing logic in
    here feels a bit dirty, but hey it works. Perhaps refactor if it starts
    getting out of hand.
    """

    # Only build a non-trivial conditional if it's a subset of all supported
    # architectures. targets. Arch conditions look like:
    #   (current_cpu == "arm" || (current_cpu == "arm" && arm_use_neon))
    arch_conditions = []
    if self.architectures != set(SUPPORTED_ARCHITECTURES):
      for arch in self.architectures:
        if arch == 'arm-neon':
          arch_conditions.append('(current_cpu == "arm" && arm_use_neon)')
        elif arch == 'ia32':
          arch_conditions.append('current_cpu == "x86"')
        else:
          arch_conditions.append('current_cpu == "%s"' % arch)

    # Only build a non-trivial conditional if it's a subset of all supported
    # targets. Branding conditions look like:
    #   (ffmpeg_branding == "Chrome" || ffmpeg_branding == "ChromeOS")
    branding_conditions = []
    if self.targets != set(SUPPORTED_TARGETS):
      for branding in self.targets:
        branding_conditions.append('ffmpeg_branding == "%s"' % branding)

    # Platform conditions look like:
    #   (is_mac || is_linux)
    platform_conditions = []
    if (self.platforms != set(SUPPORTED_PLATFORMS) and
        self.platforms != set(['linux'])):
      for platform in self.platforms:
        platform_conditions.append('is_%s' % platform)

    # Remove 0-lengthed lists.
    conditions = filter(None, [' || '.join(arch_conditions),
                               ' || '.join(branding_conditions),
                               ' || '.join(platform_conditions)])

    # If there is more that one clause, wrap various conditions in parens
    # before joining.
    if len(conditions) > 1:
       conditions = [ '(%s)' % x for x in conditions ]

    stanza = ''
    # Output a conditional wrapper around stanzas if necessary.
    if conditions:
      stanza += GN_CONDITION_BEGIN % ' && '.join(conditions)
      def indent(s):
        return '  %s' % s
    else:
      def indent(s):
        return s

    sources = sorted(n.replace('\\', '/') for n in self.sources)

    # Write out all C sources.
    c_sources = filter(IsCFile, sources)
    if c_sources:
      stanza += indent(GN_C_SOURCES_BEGIN)
      for name in c_sources:
        stanza += indent(GN_SOURCE_ITEM % (name))
      stanza += indent(GN_SOURCE_END)

    # Write out all assembly sources.
    gas_sources = filter(IsGasFile, sources)
    if gas_sources:
      stanza += indent(GN_GAS_SOURCES_BEGIN)
      for name in gas_sources:
        stanza += indent(GN_SOURCE_ITEM % (name))
      stanza += indent(GN_SOURCE_END)

    # Write out all assembly sources.
    yasm_sources = filter(IsYasmFile, sources)
    if yasm_sources:
      stanza += indent(GN_YASM_SOURCES_BEGIN)
      for name in yasm_sources:
        stanza += indent(GN_SOURCE_ITEM % (name))
      stanza += indent(GN_SOURCE_END)

    # Close the conditional if necessary.
    if conditions:
      stanza += GN_CONDITION_END
    else:
      stanza += '\n'  # Makeup the spacing for the remove conditional.
    return stanza


def CreatePairwiseDisjointSets(sets):
  """ Given a list of SourceSet objects, returns the pairwise disjoint sets.

  NOTE: This isn't the most efficient algorithm, but given how infrequent we
  need to run this and how small the input size is we'll leave it as is.
  """

  disjoint_sets = list(sets)

  new_sets = True
  while new_sets:
    new_sets = False
    for pair in itertools.combinations(disjoint_sets, 2):
      intersection = pair[0].Intersect(pair[1])

      # Both pairs are already disjoint, nothing to do.
      if intersection.IsEmpty():
        continue

      # Add the resulting intersection set.
      new_sets = True
      disjoint_sets.append(intersection)

      # Calculate the resulting differences for this pair of sets.
      #
      # If the differences are an empty set, remove them from the list of sets,
      # otherwise update the set itself.
      for p in pair:
        i = disjoint_sets.index(p)
        difference = p.Difference(intersection)
        if difference.IsEmpty():
          del disjoint_sets[i]
        else:
          disjoint_sets[i] = difference

      # Restart the calculation since the list of disjoint sets has changed.
      break

  return disjoint_sets


def ParseOptions():
  """Parses the options and terminates program if they are not sane.

  Returns:
    The pair (optparse.OptionValues, [string]), that is the output of
    a successful call to parser.parse_args().
  """
  parser = optparse.OptionParser(
      usage='usage: %prog [options] DIR')

  parser.add_option('-s',
                    '--source_dir',
                    dest='source_dir',
                    default='.',
                    metavar='DIR',
                    help='FFmpeg source directory.')

  parser.add_option('-b',
                    '--build_dir',
                    dest='build_dir',
                    default='.',
                    metavar='DIR',
                    help='Build root containing build.x64.linux, etc...')

  parser.add_option('-g',
                    '--output_gn',
                    dest='output_gn',
                    action="store_true",
                    default=False,
                    help='Output a GN file instead of a gyp file.')

  parser.add_option('-p',
                    '--print_licenses',
                    dest='print_licenses',
                    default=False,
                    action="store_true",
                    help='Print all licenses to console.')

  options, args = parser.parse_args()

  if not options.source_dir:
    parser.error('No FFmpeg source directory specified')
  elif not os.path.exists(options.source_dir):
    parser.error('FFmpeg source directory does not exist')

  if not options.build_dir:
    parser.error('No build root directory specified')
  elif not os.path.exists(options.build_dir):
    parser.error('FFmpeg build directory does not exist')

  return options, args


def WriteGyp(fd, build_dir, disjoint_sets):
  fd.write(COPYRIGHT)
  fd.write(GYP_HEADER)

  # Generate conditional stanza for each disjoint source set.
  fd.write(GYP_CONDITIONAL_BEGIN)
  for s in disjoint_sets:
    fd.write(s.GenerateGypStanza())
  fd.write(GYP_CONDITIONAL_END)

  fd.write(GYP_FOOTER)


def WriteGn(fd, build_dir, disjoint_sets):
  fd.write(COPYRIGHT)
  fd.write(GN_HEADER)

  # Generate conditional stanza for each disjoint source set.
  for s in reversed(disjoint_sets):
    fd.write(s.GenerateGnStanza())


# Lists of files that are exempt from searching in GetIncludeSources.
IGNORED_INCLUDE_FILES = [
  # Chromium generated files
  'config.h',
  os.path.join('libavutil', 'avconfig.h'),
  os.path.join('libavutil', 'ffversion.h'),

  # Current configure values are set such that we don't include these (because
  # of various defines) and we also don't generate them at all, so we will fail
  # to find these because they don't exist in our repository.
  os.path.join('libavcodec', 'aacps_tables.h'),
  os.path.join('libavcodec', 'aacsbr_tables.h'),
  os.path.join('libavcodec', 'aac_tables.h'),
  os.path.join('libavcodec', 'cabac_tables.h'),
  os.path.join('libavcodec', 'cbrt_tables.h'),
  os.path.join('libavcodec', 'mpegaudio_tables.h'),
  os.path.join('libavcodec', 'pcm_tables.h'),
  os.path.join('libavcodec', 'sinewin_tables.h'),
]


# Known licenses that are acceptable for static linking
# DO NOT ADD TO THIS LIST without first confirming with lawyers that the
# licenses are okay to add.
LICENSE_WHITELIST = [
  'BSD (3 clause) LGPL (v2.1 or later)',
  'ISC GENERATED FILE',
  'LGPL (v2.1 or later)',
  'LGPL (v2.1 or later) GENERATED FILE',
  'MIT/X11 (BSD like)',
  'Public domain LGPL (v2.1 or later)',
]


# Files permitted to report an UNKNOWN license. All files mentioned here should
# give the full path from the source_dir to avoid ambiguity.
# DO NOT ADD TO THIS LIST without first confirming with lawyers that the files
# you're adding have acceptable licenses.
UNKNOWN_WHITELIST = [
  # From of Independent JPEG group. No named license, but usage is allowed.
  os.path.join('libavcodec', 'jrevdct.c'),
  os.path.join('libavcodec', 'jfdctfst.c'),
  os.path.join('libavcodec', 'jfdctint_template.c'),
]


# Regex to find lines matching #include "some_dir\some_file.h".
INCLUDE_REGEX = re.compile('#\s*include\s+"([^"]+)"')

# Regex to find whacky includes that we might be overlooking (e.g. using macros
# or defines).
EXOTIC_INCLUDE_REGEX = re.compile('#\s*include\s+[^"<\s].+')

# Prefix added to renamed files as part of
RENAME_PREFIX = 'autorename'


def GetIncludedSources(file_path, source_dir, include_set, depth = 0):
  """ Recurse over include tree, accumulating absolute paths to all included
  files (including the seed file) in include_set.

  Pass in the set returned from previous calls to avoid re-walking parts of the
  tree. Given file_path may be relative (to options.src_dir) or absolute.

  NOTE: This algorithm is greedy. It does not know which includes may be
  excluded due to compile-time defines, so it considers any mentioned include.

  NOTE: This algorithm makes hard assumptions about the include search paths.
  Paths are checked in the order:
  1. Directory of the file containing the #include directive
  2. Directory specified by source_dir

  NOTE: Files listed in IGNORED_INCLUDE_FILES will be ignored if not found. See
  reasons at definition for IGNORED_INCLUDE_FILES.
  """
  # Use options.source_dir to correctly resolve relative file path. Use only
  # absolute paths in the set to avoid same-name-errors.
  if not os.path.isabs(file_path):
    file_path = os.path.abspath(os.path.join(source_dir, file_path))

  current_dir = os.path.dirname(file_path)

  # Already processed this file, bail out.
  if file_path in include_set:
    return include_set

  include_set.add(file_path)

  for line in open(file_path):
    include_match = INCLUDE_REGEX.search(line)

    if not include_match:
      if EXOTIC_INCLUDE_REGEX.search(line):
        print 'WARNING: Investigate whacky include line:', line
      continue;

    include_file_path = include_match.group(1)

    # These may or may not be where the file lives. Just storing temps here
    # and we'll checking their validity below.
    include_path_in_current_dir = os.path.join(current_dir, include_file_path)
    include_path_in_source_dir = os.path.join(source_dir, include_file_path)
    resolved_include_path = ''

    # Check if file is in current directory.
    if os.path.isfile(include_path_in_current_dir):
      resolved_include_path = include_path_in_current_dir;
    # Else, check source_dir (should be FFmpeg root).
    elif os.path.isfile(include_path_in_source_dir):
      resolved_include_path = include_path_in_source_dir
    # Else, we couldn't find it :(.
    elif include_file_path in IGNORED_INCLUDE_FILES:
      continue
    else:
      exit('Failed to find file', include_file_path)

    # At this point we've found the file. Check if its in our ignore list which
    # means that the list should be updated to no longer mention this file.
    if include_file_path in IGNORED_INCLUDE_FILES:
      print('Found %s in IGNORED_INCLUDE_FILES. Consider updating the list '
            'to remove this file.' % str(include_file_path))

    GetIncludedSources(resolved_include_path, source_dir, include_set, depth + 1)


def CheckLicenseForSource(source, source_dir, print_licenses):
  # Assumed to be two back from source_dir (e.g. third_party/ffmpeg/../..).
  source_root = os.path.abspath(
      os.path.join(source_dir, os.path.pardir, os.path.pardir))

  licensecheck_path = os.path.abspath(os.path.join(
      source_root, 'third_party', 'devscripts', 'licensecheck.pl'));
  if not os.path.exists(licensecheck_path):
    exit('Could not find licensecheck.pl: ' + str(licensecheck_path))

  check_process = subprocess.Popen([licensecheck_path,
                                    '-l', '100',
                                    os.path.abspath(source)],
                                    stdout=subprocess.PIPE,
                                    stderr=subprocess.PIPE)
  stdout, stderr = check_process.communicate()

  # Get the filename and license out of the stdout. stdout is expected to be
  # "/abspath/to/file: *No copyright* SOME LICENSE".
  filename, license = stdout.split(':', 1)
  license = license.replace('*No copyright*', '').strip()
  rel_file_path = os.path.relpath(filename, os.path.abspath(source_dir))

  if (license in LICENSE_WHITELIST or
     (license == 'UNKNOWN' and rel_file_path in UNKNOWN_WHITELIST)):
    if print_licenses:
      print filename, ':', license
    return True

  print 'UNEXPECTED LICENSE: %s: %s' % (filename, license)
  return False


def CheckLicensesForStaticLinking(disjoint_sets, source_dir, print_licenses):
  # Build up set of all sources and includes.
  sources_to_check = set()
  for source_set in disjoint_sets:
    for source in source_set.sources:
      GetIncludedSources(source, source_dir, sources_to_check)

  # Check licenses for all included sources.
  all_checks_passed = True
  for source in sources_to_check:
    if not CheckLicenseForSource(source, source_dir, print_licenses):
      all_checks_passed = False
  return all_checks_passed


def FixObjectBasenameCollisions(disjoint_sets, all_sources):
  """ Mac libtool warns needlessly when it encounters two object files with
  the same basename in a given static library. See more at
  https://code.google.com/p/gyp/issues/detail?id=384#c7

  Here we hack around the issue by copying and renaming source files with the
  same base name to avoid the collision. The original is kept to keep things
  simple when merging from upstream ffmpeg.

  If upstream changes the name such that the collision no longer exists, we
  detect the presence of a renamed file in all_sources which is overridden and
  warn that it should be removed."""

  SourceRename = collections.namedtuple("SourceRename", "old_name, new_name")
  known_basenames = set()
  all_renames = set()

  for source_set in disjoint_sets:
    # Track needed adjustments to change when we're done with each SourceSet.
    renames = set()

    for source_name in source_set.sources:
      folder, basename = os.path.split(source_name)

      # Sanity check: source set should not have any renames prior to this step.
      if RENAME_PREFIX in basename:
        exit('Found unexpected renamed file in SourceSet: %s' % basename)

      # Craft a new unique basename from the path of the colliding file
      if basename in known_basenames:
        name_parts = source_name.split(os.sep)
        name_parts.insert(0, RENAME_PREFIX)
        new_basename = '_'.join(name_parts)
        new_source_name = os.sep.join([folder, new_basename])

        renames.add(SourceRename(source_name, new_source_name))
      else:
        known_basenames.add(basename)

    for rename in renames:
      print "fixing basename collision: %s -> %s" % (rename.old_name, rename.new_name)

      shutil.copy2(rename.old_name, rename.new_name)
      source_set.sources.remove(rename.old_name);
      source_set.sources.add(rename.new_name)
      all_renames.add(rename.new_name)

  # Now, with all collisions handled, walk the set of known sources and warn
  # about any renames that were not replaced. This should indicate that an old
  # collision is now resolved by some external/upstream change.
  for source_name in all_sources:
    if RENAME_PREFIX in source_name and source_name not in all_renames:
      print "WARNING: %s no longer collides. DELETE ME!" % source_name


def main():
  options, args = ParseOptions()

  # Generate map of FFmpeg source files.
  source_dir = options.source_dir
  source_files = GetSourceFiles(source_dir)
  object_to_sources = GetObjectToSourceMapping(source_files)

  sets = []

  for arch in SUPPORTED_ARCHITECTURES:
    for target in SUPPORTED_TARGETS:
      for platform in SUPPORTED_PLATFORMS:
        # Assume build directory is of the form build.$arch.$platform/$target.
        name = ''.join(['build.', arch, '.', platform])
        build_dir = os.path.join(options.build_dir, name, target)
        if not os.path.exists(build_dir):
          continue
        print 'Processing build directory: %s' % name

        object_files = GetObjectFiles(build_dir)

        # Generate the set of source files to build said target.
        s = GetSourceFileSet(object_to_sources, object_files)
        sets.append(SourceSet(s, set([arch]), set([target]), set([platform])))

  sets = CreatePairwiseDisjointSets(sets)

  if not sets:
    exit('ERROR: failed to find any source sets. ' +
         'Are build_dir (%s) and/or source_dir (%s) options correct?' %
              (options.build_dir, options.source_dir))

  FixObjectBasenameCollisions(sets, source_files);

  if not CheckLicensesForStaticLinking(sets, source_dir,
                                       options.print_licenses):
    exit ('GENERATE FAILED: invalid licenses detected.')
  print 'License checks passed.'

  # Open for writing.
  if options.output_gn:
    outfile = 'ffmpeg_generated.gni'
  else:
    outfile = 'ffmpeg_generated.gypi'
  output_name = os.path.join(options.source_dir, outfile)
  print 'Output:', output_name

  with open(output_name, 'w') as fd:
    if options.output_gn:
      WriteGn(fd, options.build_dir, sets)
    else:
      WriteGyp(fd, options.build_dir, sets)

if __name__ == '__main__':
  main()
